There has been uncertainty in the taxonomy of this genus, reflected in the range of treatments from that of Avdeyev (Izv. Akad. Nauk Tadzh. SSR, Biol. Nauk 4(93): 11-17. 1983), who recognized only one species with two subspecies, to Bartish et al. (Syst. Bot. 27: 41-54. 2002), who suggested on the basis of both morphological and molecular data that there is a good case for recognizing seven species plus a total of ten further subspecies. This latter view is accepted here. Flowering material is relatively rarely collected and the following key is based largely on fruiting material.

Seven species: from NW Europe to E Asia, with a center of diversity on the Qinghai-Xizang plateau, most species associated with seasonally moist situations; seven species (four endemic) in China.